1. Field of the Invention
The present general inventive concept relates to an image forming apparatus and a control method thereof, and, more particularly, to an image forming apparatus in which respective colors of developer images may be transferred to the same position on an intermediate transfer belt, and a control method thereof.
2. Description of the Related Art
Generally, color image forming apparatuses may be classified into a multi-pass type color image forming apparatus in which a color image is formed using a single photoconductor, and a single-pass type color image forming apparatus in which a color image is formed using a plurality of photoconductors.
The multi-pass type color image forming apparatus includes an intermediate transfer belt. After different colors of developer images formed on the plurality of photoconductors are transferred to and overlap one another on the intermediate transfer belt thus forming a primary transfer image, the intermediate transfer belt performs secondary transfer of the primary transfer image onto a recording medium.
In this case, a plurality of developer images are formed on the respective photoconductors by corresponding developing devices and thereafter, are transferred to and overlap one another on the intermediate transfer belt. Accordingly, to achieve an even primary transfer image having no color deviation between the different colors of developer images when the respective developer images formed on the photoconductors are transferred to and overlap one another on the intermediate transfer belt, it may be necessary to transfer the different colors of developer images to the same position on the intermediate transfer belt.
In a conventional method, a position identification hole is formed at a predetermined position of an intermediate transfer belt, so that an image is formed on a photoconductor in response to a signal generated when a position sensor senses the position identification hole.
If the position identification hole is sensed, a first color image, for example, a yellow developer image is formed on the photoconductor under control of a light scanning device and each developing device and thereafter, the yellow developer image is transferred to the intermediate transfer belt. In this case, simultaneously with the yellow developer image being formed on the photoconductor in response to the sensing signal of the position identification hole, a cleaning blade of a cleaning unit that comes into contact with the intermediate transfer belt is moved away from the intermediate transfer belt.
Thereafter, the remaining colors of developer images are formed respectively on the photoconductor whenever the position identification hole is sensed and thereafter, are transferred to and overlap one another on the intermediate transfer belt on which the yellow developer image has been transferred.
However, differently from the formation of the remaining colors of developer images, the cleaning blade is not completely spaced apart from the intermediate transfer belt upon formation of the first developer image, i.e. the yellow developer image. Therefore, contact friction between the intermediate transfer belt and the cleaning blade may retard the rotational velocity of the intermediate transfer belt. Consequently, this may cause color discrepancy between the different colors of developer images transferred to the intermediate transfer belt. More specifically, of the plurality of images transferred to the intermediate transfer belt, the yellow developer image may appear out of alignment with magenta, cyan and black developer images.